Architecture Dependence on the Steric Constrains of the Ligand in Cyano-Bridged Copper(I) and Copper(II)−Copper(I) Mixed-Valence Polymer Compounds Containing Diamines: Crystal Structures and Spectroscopic and Magnetic Properties

Citations Over TimeTop 10% of 2002 papers

Abstract

A family of cyano-bridged copper(II)-copper(I) mixed-valence polymers containing diamine ligands of formula [Cu(pn)(2)][Cu(2)(CN)(4)] (1, pn = 1,2-propanediamine), [Cu(2)(CN)(3)(dmen)] (2, dmen = N,N-dimethylethylenediamine), and [Cu(3)(CN)(4)(tmen)] (3, tmen = N,N,N',N'-tetramethylethylenediamine) have been prepared with the aim of analyzing how their architecture may be affected by steric constraints imposed by the diamine ligands. In the absence of diamine and with use of the voluminous NEt(4)(+) cation, the copper(I) polymer [NEt(4)][Cu(2)(CN)(3)] (4) forms. The structure of 1 consists of a three-dimensional diamond-related anionic framework host, [Cu(2)(CN)(4)](2-), and enclathrated [Cu(pn)(2)](2+) cations. The structure of 2 is made of neutral corrugated sheets constructed from fused 18-member nonplanar rings, which contain three equivalent copper(I) and three equivalent copper(II) centers bridged by cyanide groups in an alternative form. The 3D structure of 3 consists of interconnected stair-like double chains built from fused 18-member rings, which adopt a chairlike conformation. Each ring is constructed from two distorted trigonal planar Cu(I) centers, two bent seemingly two-coordinated Cu(I) centers, and two pentacoordinated Cu(II) atoms. The structure 4 is made of planar anionic layers [Cu(2)(CN)(3)](n)(n-) lying on mirror planes and NEt(4)(+) cations intercalated between the anionic layers. From the X-ray structural results and calculations based upon DFT theory some conclusions are drawn on the structure-steric factors correlation in these compounds. Compound 1 exhibits very weak luminescence at 77 K with a maximum in the emission spectrum at 520 nm, whereas compound 4 shows an intense luminescence at room temperature with a maximum in the emission spectrum at 371 nm. Polymers 2 and 3 exhibit weak antiferromagnetic magnetic exchange interactions with J = -0.065(3) and -2.739(5) cm(-1), respectively. This behavior have been justified on the basis of the sum of two contributions: one arising from the pure ground-state configuration and the other one from the charge-transfer configuration Cu(I)-CN-Cu(II)-CN-Cu(II) that mixes with the ground-state configuration.

Related Papers

• → Steric Effects on Multivalent Ligand-Receptor Binding: Exclusion of Ligand Sites by Bound Cell Surface Receptors(1999)150 cited
• → Steric Parameters of Conformationally Flexible Ligands from X-ray Structural Data. 1. P(OR)₃ Ligands in Equivalent Ligand Environments(2000)23 cited
• → Synthesis of alkynyl(tricarbonyl)rhenium complexes containing a lightly coordinated diamine ligand(2008)10 cited
• → The nature of seat-ligand fitting in coordination space. Part 3. Ligand exchange and rearrangement due to awkward packing(1987)12 cited
• → Quantification of the Steric Properties of 1,8-Naphthyridine Based Ligands in Dinuclear Complexes(2022)